Not applicable.
Not applicable.
Not applicable.
1. Field of the Invention
The invention relates to communications systems, and in particular, to communications systems that provide an interface between analog telephony systems and Asynchronous Transfer Mode (ATM) systems.
2. Background
The telephone wires to the residence are known as the local loop. The local loop has primarily been used to carry analog telephony traffic. The primary device for providing analog telephony at the local level is the class 5 telephone switch. Class 5 telephone switches are well known. Class 5 telephone switches are complex and expensive to deploy and operate. They are also relatively difficult to re-program and re-configure in order to implement new services. One example is the current problem class 5 telephone switches are having handling large amounts of Internet traffic.
The class 5 telephone switch communicates with an analog telephone using the analog telephony signals in the well-known analog telephony format. The class 5 telephone switch provides power to the telephone. The class 5 telephone switch detects off-hook current caused by the telephone and provides the telephone with dial tone. The caller generates Dual-Tone Multi-Frequency (DTMF) signals. The class 5 telephone switch detects the DTMF signals and initiates the call in the network. When the far-end telephone is ringing, the class 5 telephone switch plays a ringback tone to the caller. If the far-end telephone is busy, the class 5 telephone switch plays a busy tone to the caller. On incoming calls, the class 5 telephone switch provides ring current to the telephone.
Digital Loop Carrier (DLC) devices have been deployed to provide a digital interface between an analog telephone and a class 5 telephone switch. DLC devices are well-known. DLC devices use the analog telephony format to communicate with the telephone, but they use a digital format to communicate with the class 5 telephone switch. The digital format is specified by Bellcore Technical Reference 303 (TR-303).
Digital Subscriber Line (DSL) technology has been developed to provide greater bandwidth to the local loop. DSL technology superimposes high bandwidth data over the analog telephony traffic on the local loop. This high bandwidth data is transparent to the analog telephony operation of the local loop. At the central office, the high bandwidth data is removed from the twisted pair and provided to a separate data network. The analog telephony traffic remains on the twisted pair and is provided to a class 5 telephone switch. DSL devices do not operate on local loops using DLC devices.
DSL technology allows high bandwidth data and analog telephony traffic to co-exist on the local loop. The analog telephony traffic is still handled by a class 5 telephone switch in the conventional manner, but the high bandwidth data is removed from the line before the class 5 telephone switch. A typical application is to use DSL technology to provide a high speed Internet connection while using the class 5 telephone switch to handle the analog telephony traffic. This provides an advantage to established local networks because it removes the Internet traffic loads from the class 5 telephone switches, and it allows the local networks to continue to leverage their existing class 5 telephone switches for the analog telephony traffic.
Asynchronous Transfer Mode (ATM) and Synchronous Optical Network (SONET) technologies have also been developed to provide broadband transport and switching capability to Local Area Networks (LANs), Wide Area Networks (WANs), and other networks. Prior systems do not contemplate converting the analog telephony traffic to ATM before it is placed on the DSL local loop. This is because standard class 5 telephone switches on the network side of the local loop do not typically handle ATM traffic. As a result, ATM technology has not been combined with DSL technology to carry residential telephone traffic. The analog telephony traffic carried by a DSL local loop still requires processing by a complex and expensive class 5 telephone switch.
Despite the availability the above-mentioned technologies, a large customer base remains that chooses not to migrate from their existing analog telephone service using conventional telephones. Telephony hubs are being developed to service these customers. The telephony hub provides traditional analog telephone service over local loops to the customers choosing such service. The telephony hub is capable of providing this traffic to an advanced communications network in the ATM format. The telephony hub also provides digital telephone service for telephones that are connected to a DLC device.
This situation is tolerable for established networks with a large pre-existing class 5 telephone switch network, but the situation is problematic for new entrants into the local market. The new entrants do not have an existing network of class 5 telephone switches. With imminent opportunities to compete for local telephone services, there is a need for an alternative to the class 5 telephone switch that can be used to offer telephone services in the local environment. This alternative should provide advanced communications technology, but should also provide traditional telephony services to customers who desire conventional telephone services.
The invention overcomes the above problems by providing an ATM communications system that provides the option of advanced communications services or conventional telephone service to the customer. Advantageously, the communications system does not require the widespread deployment of class 5 telephone switches to provide telephone service.
The invention is an ATM communications system for providing telephony service. A residential communications hub is located at a residence and communicates with the telephones at the residence using the analog telephony format. The residential communications hub converts between the analog telephony format and the ATM format. The residential communications hub is connected to a DSL mux by telephone wiring that carries the ATM/DSL format. The residential communications hub and the DSL mux communicate using the ATM/DSL format. The DSL mux converts between the ATM/DSL format and the ATM/SONET format. The DSL mux is connected to the an ATM switch by a broadband connection that carries the ATM/SONET format. The DSL mux and the ATM switch communicate using the ATM/SONET format. The ATM switch establishes ATM communications paths for the telephone service. A telephony hub is connected to telephones by telephone wiring that carries the analog telephony format. The telephony hub communicates with the telephones using the analog telephony format. The telephony hub is connected to the ATM switch by a broadband connection that carries the ATM/SONET format. The telephony hub and the ATM switch communicate using the ATM/SONET format.